Sam Givhan knows all about change. The 69-year-old proprietor of Givhan Land and Cattle Company, in Dallas County, Ala., can remember when operations on the farm, known as Lime Ridge in his grandparents’ day, were powered by mules and hand labor.

Today, Givhan and his wife, Lynne, farm some 4,500 acres, including the original 600 acres owned by his grandmother at the turn of the last century.

“My grandmother had a self-sufficient farm,” Givhan says, and her operations included dairy cows, hogs, a smokehouse, even a commissary. “Most of the food ...